Résumé
The strain accumulating between M9-class earthquakes is a major component of the active deformation that contributes to resolve the pattern of seismic cycle at plate boundary zones. Recent geodetic and seismotectonic works constrain the nearly equal 500-km-long 2011 Tohoku megathrust rupture and related slip distribution. Here, we investigate marine terraces at 132 sites and palaeotsunami deposits at 7 estuaries in east Honshu and assess a prevailing late Quaternary coastal uplift and seismic coupling on a segmented Japan subduction zone. The tectonic process shows 0.2 and 0.4 mm/yr uplift rate of Pleistocene marine terraces in northern Tohoku, and 0.1 - 0.2 mm/yr along the Sanriku and southern Tohoku coastline. This variation depicts two active tectonic sub-regions where the area of low uplift rate correlates with the 2011 subsidence. Holocene benches and notches reveal nearly equal 1.1 mm/yr uplift rate in northern Tohoku which denotes clear upheaval acceleration during late Quaternary. The palaeotsunami record in the last 7 kyr on the Sanriku and Sendai coastline constrains the 400 - 800 years recurrence interval of palaeoearthquakes. Our modelling of crustal deformation indicates how the successive coastal subsidence during M9-class earthquakes may be concealed by the long term upheaval. [Copyright Author(s) 2013. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]